Lactonization of ω-Hydroxy Esters over Hydrous Zirconium(IV) Oxide

The lactonization of ω-hydroxy esters was carried out by catalysis with hydrous zirconium(IV) oxide. In the flow reaction system, ω-hydroxy esters were efficiently converted to give the corresponding lactones. In particular, it is noteworthy that heptanolide is obtained in good yield. In addition, it is possible to produce a large quantity of lactones in this catalyst system.